Engine synchronization



Sept.2, 1941. QLMWNEIL 2,254,970

ENGINE SYNCHRONIZATION Filed Sept. 20, 1940 v 2 Sheets-Sheep 1 INVENTORLC/mr/es 1: Mac IVs/7 74,4425; W

RNEY.

V Patented Sept. 1941 UNITED STAT ES PATENT OFFICE ENGINESYNCHRONIZATION Charles I. MacNeil, Glen Ridge, N. 3., assignor toBendix Aviation Corporation,

South Bend,

Ind., a corporation of Delaware Application September 20, 1940, SerialNo. 357,642

'6 Claims.

several definitions of the invention set forth in the appended claims.

Fig. 1 is a schematic representation of .a synchronizing systemembodying the invention;

Fig. 2 is a second schematic representation of the system in Fig. 1including certain parts of available for commercial use. This may alsobe due to the complexity and consequent ness of devices heretoforeknown.

Most of the priorsynchronizers involve use of heavy gearing,- electricalapparatus, or mechanism that must be constantly checked and preciselyexpensiveadjusted tomaintain accuracy. An object of the presentinvention is to provide a synchronizing apparatus that will performaccurately, will not require frequent adjustment, and will not involveheavy gearing or electrical energy for its operation. s Y

Another object of the invention is to provide a synchronizer that isoperable'by utilization of a relatively small amount of hydraulic power,and with the meet small and inexpensive, yet highly emcient anddependable hydraulic mechanism. 7

Another object is ;to provide a hydraulic synchronizing mechanism,including a hydraulically operated 'indicater (Synchroscopeh andalterthe system which do not appear inFig. 1; and

Fig. 3 is a view in elevation, with certain parts shown in mechanicalsection, of the preferred structural arrangement ofr'the piping andassociated flow control means for the system shown in Figs. 1 and 2. l

Referring principally to Figs. 1 and 2, reference characters H and I2designate apair of internal combustion engines which may be assumed tobe mounted on opposite sides of the center lines of an aircraft, andadapted to have their speeds controlled in any of the usual ways, suchas by native manual controlmeans for manualsynchronization wheneverdesired.

A. further object is to pro'vide'ajhydraulic synchronizerthat isself-containedyet readily applicable to other hydraulic mechanism, (suchas a hydraulically operated; propeller pitch control,

of the type shown in Woodward @Patent No.

variation of their throttle settings, to vary the amount of fuelsupplied thereto, or by variation of the pitch angle of the blades ofthe propellers (shownat I3 and H for the respective engines II and I2.)One form of propeller pitch mechanism is indicated schematically in Fig.l, and for purposes of illustration the invention is shown as appliedtothe'spring loading member l6 of the governor ll of such a pitch varyingmechanism,

wherefore the synchronizing mechanism to be described operates throughsuch spring loading,

member ii to control the pitch of the propeller blades i4 therebycontrolling the speed 01' the I engine l2 by causing it to synchronizeat all times with the speed of the master engine I I; but it is to beunderstood that the invention is equally applicable to any othersuitable form of speed varying mechanism employable to eifect such cweveis ai plicableto anygtype of speed controllingagency', -wlietl'ier.such agency acts to vary the. propeller .pitch,*fuel supplyfor,

other speed controllingfactor of the engine.

Other objects'a gi 'featuresoi' the invention will i become apparentuponexamination of the following specification and theaccompanying-drawings;

wherein the preferred embodiment of the invenje ever, that the drawingsare merely illustrative and that the scope of the invention extends toother embodiments which fall within'any of the synchronization. I

The system,the-.invention includes a pump 4112i adapted to drivenbysuitable connections, cours ngun l8,,1940) 'wlieije such hydraulicmechanism constitutes a spitedl'controlling agency for the engine or:,hgines to be; synchronized,

not shown, operated by the engine II, a similar 24,25, 26, 2'! and 28forming a complete circuit to and from the pumps 2| and 22 (the conduit23 being assumed to be theoutlet or pressure side of the pump 2|, andconduit 26 the outlet or pressure side of pump 22),; a pair ofexpansible elements 3| and 32 having fluid conducting comso municationwith the pipes 24 and 21, respectively,

as; indicated at 33 and 34, a visual indicator 36 which-may be ofthedifferential pressure operated tion is illustrated. It is tobeunderstood, how

type and for'which purpose it will have fluid conducting communicationwith'the pipes 24 and 21,

able reversible pump 43 by which synchronism between the engines II andI2 may be maintained manually (and observed on the indicator 36)whenever for any reason'it is necessary or desirable to discontinueoperation of the automatic circuit which includes the pumps 2| and 22.Ad-

ditional desirable parts include a pair of pressetting of one of thevalves sufllciently to allow leakage around the associated pump,equivalent to that which occurs by reason of a lower efficiency in theoperation of the other pump. Another desirable addition to the system isthe pair of coiled sections iii and G2 in the pipes 24 and 21,respectively, by which there is provided op-' portunity for sufficientdissipation of heat generated in the system to maintain a normaltemperature therein at all times.

While the governor form of speed control that is illustrated in Fig. 1is not per se, a part of the present invention-and is more fullydescribed in U. S. Patent No. 2,204,640 granted to Woodward-it may behelpful to point out herein that such a mechanism includes, as essentialparts thereof, a slide valve II adapted to reciprocate in a valvehousing 12 having ports therein to establish, when the speed conditionswarrant, a circuit for the flow of fluid from a suitable source I2, andpumps 14 and 15 to a -valve mechanism and servo-motor 16 adapted toexert pressure to turn the blades of the propeller l4 against theopposing torque of centrifugal weights, as in the well-known type ofhydraulic pitch varying mechanism referred to in said patent to Woodwardand also in various patents issued to Frank W. Caldwell, among which maybe noted Patent No. 2,l63,663. It will be understood that the effect ofthe valve II in controlling the operation of such pitchvarying'mechanism is governed by the loading of the spring 19 of thegovernor, as the said loading varies the effect of speed upon the amountof movement of the valve Accordingly, any mechanism which varies thisspring loading in response to a deviation in the speed of thesubordinate engine l2, with respect to the master engine II, will beeffective (through the corresponding shift in the position of valve 1|)to produce a corresponding change in the angles of the blades of thepropeller l4,

and thereby to restore the speed of the engine l2 to synchronism withthat of engine II.

It will be apparent that if motion occurs at the Q free ends of theexpansible bellows 3| and 32--the ends thereof which receive theconduits 33 and 34, respectively, being held stationary asindicated-such motion can be communicated to the spring loading memberIS of the governor mechanism by interposing, between said bellows andsaid member IS, a suitable linkage such, for ex ample, as that indicatedat BI, 82 and 83; the

member 8| being a link pivotally connected to the member 82 by asuitable pin 8, and having a ball and socket fulcrum 86 which causes thesaid lever 8|.to swing about said ball and socket connection 86 inresponse to movement of either bellows 3| and 32, and the correspondingreciprocal movement of the connecting rod 82 which'links the free endsof the bellows 3| and 32 and therefore partakes of any movement ments.Such a swinging of the lever 8| will produce a corresponding linearmotion of the member i8 by reason of the pin and slot'connectionindicated at O3, and there will be a corresponding variation in theloading of the spring ,19. Such variation will allow the governorweights to act, through valve II, to restore synchronism as heretoforeexplained. a i

It will further be understood that any devia-' tion in the speed of theengine '|2 from that of the master engine II will result in acorresponding speed deviation as between the pumps 22 and 2| driven bythe respective engines, and this dif- 22, and point A reflecting thepressure at the output of the pump 2|. Any pressure difference at thesetwo points will, of course, result in movement of the bellows actuatedrod 82, due to the uneven expansion of the two bellows 3| and 32 byreason of the'difierence in the pressures therein. Likewise any suchpressure differences will be re-, flected in the differential pressuregauge 36, so that'the operator of the craft will be constantly informed,by this visual means, as to the synchronism or non-synchronism of thetwo engines. It will further be apparent that as the governor mechanismresponds to such movement of linkage 22, BI and 83, the resulting changein the speed of engine |2 toward that of the master engine II, willproduce a corresponding diminution in the degree of pressure difierenceat the points A and B, due to the resulting change in speed of the pump22 toward synchronism with pump 2|. As heretofore indicated, theinvention preferably includes shut-off valvesJL fl (Fig. 2) by which themain circuit, including the pumps 2| and 22, may be completely cut offfrom the bellows II and 32; but the bellows may nevertheless be operatedby manipulation of the hand pump 43. On any such occasion a manualactuation of the pump 43 will operate to shift the desired amount offluid from'the bellows 3| to the bellows 22 (or vice versa, according tothe direction of rotation of the pump) and in this manner the linkage82, 8| and 83 will be brought into operation to restore synchronism bythe same process as that which occurs during the functioning of theautomatic controls including the pumps 2| and 22. If desired, the valvesll, 42-may bemechanically interlinked so that a single manual operationmay be effective to close off both valves simultaneously; or this may bedone by resorting disposed conduits 92 and 93 to provide a unitarycontrol of flow therethrough. These ooaxially disposed pipes 82 and 93may be inserted in the system at some point along the pipes 24 and 21,the connection between the coaxial pipes and the parallel pipes beingeffected by utilizing a fluid chamber, as indicated at 94, through whichthe pipe 24, for example, may pass to become the inner pipe of thecoaxial group, while the other pipe 21 is caused to terminate in saidchamber as would also the outer pipe 92 of the coaxial group. With thearrangement as shown it will be seen that a ninety-degree rotationof therotor of valve 9| may operate to simultaneously establish ordisestablish communication between theof either of said ele- 7 right andleft hand sections of the coaxial pipes 2,254,970 92 and 93; and byproviding at the opposite end a chamber similar to the chamber 94, thesaid coaxial pipes will, of course, operateto feed fluid back to thesystem shown .in Fig. 1 and Fig.2 without any other change in thesystem. It will further be understood that such coaxial pipes may beused at any other point in the system where parallel pipes are employed,and where so used will have the advantage of reducing the i I more thantwo engines, in which case the speed of the master engine may-bemaintained for eachofthe subordinate engines by adding to so long assaid engines remain synchronized, means for cutting off the flow offluid in each of said fluid conduits, and manually operable means incircuit with both said fluid receiving means to regulate the pressuretherein manually during those periods when fluid flow in said fluidconduits hasbeen cutoff by operation of ,said cut-ofi means, saidmanually operable means including a hand pump for transferring fluidfrom one of saidfluid receiving means to the other and thereby causingmovement of said mechanical linkage in a direction corresponding to thedirection of fluid transfer.

3. In combination with a pair of engines, at least one having speedregulating means associated therewith; a pair of fluid pumps rotatableto the other engine, meansresponsive to a difthe system additionalpumping mechanism corference in the pressures developed by said pumps tochange the setting of said speed regulating means, said last-named meanscomprising fluid receiving means in communication with said pumps, amechanical linkage connecting said fluid receiving means with said speedregulating means, means for cutting oil the flow of fluid from saidpumps to said fluid receiving means,

least one having speed regulating means associated therewith, a pair offluid pumps rotatable with said engines, one at aspeed corresponding toone engine, the other at a speed corresponding to the other engine,means responsive to a difference in the pressures developed by saidpumps to change the setting of said speed regulating means, saidlast-named means comprising fluid conduits connecting the inlet of eachpump with the outlet of the other, fluid receiving means incommunication with one of said conduits, additional fluid receivingmeans in communication with the other of said conduits, a mechanicallinkage connecting said fluid receiving means with said speed regulatingmeans, said linkage being held against movement by the equal andopposing pressures of said fluid receiving means, so long as saidengines remain synchronized, means for cutting oil the flow of fluid ineach of said fluid conduits, and manually operable means and manuallyoperable means in circuit with both said fluid receiving means toregulate the pressure therein manually during those periods when fluidflow has been cut ofi by operation of said cut-oflmeans, said manuallyoperable means including a hand pump for transferring fluid in saidfluid receiving means and thereby causing movement of said mechanicallinkage in a, direction corresponding to the direction of fluid transincircuit with both said fluid receiving means duits has been cut off byoperation of said cut-ofi means.

- 2. In combination with a pair of engines, at-

least one having speed regulating means associated therewith, a pair offluid pumps rotatable with said engines, one at a speed corresponding toone engine, the other at a speed corresponding to the other engine,means responsive to a difference in the pressures developed by saidpumps to change the setting of said speed regulating means,saidlast-named means comprising fluid conduits connecting the inlet ofeach the -outlet'of the other, fluid receiving means in communicationwith one of said conduits, additional fluid receiving means incommunication with the other of said conduits, a mechanicallinkageconnecting said fluid receiving means with said speed regulating means,said linkage being held against movement by the equal and opposingpressures of said fluid.receiving means,

pump with fer, and said cut-off means including a valve for each of saidconduits and a single operating means for both said valves. V

4. In combination with a pair of engines, at least one having speedregulating means associated therewith, a pair of fluid pumps rotatablewith said engines, one at a speed corresponding tooneengine, the otherat a speed corresponding to the other engine, means responsive to adifferencein the pressures developed by said pumps to change the settingof said speed regulating means, said last-named means including fluidconduits connecting the inlet of each pump with the outlet of the other,and said fluid conduits having sections disposed in coaxialrelationship, means including a single rotary valve for cutting oflfluid flow in said coaxial conduit sections simultaneously, and manuallyoperable means for changing the setting of said speed regulating meansduring the periods when fluid flow through said fluid conduits isinterrupted by virtue of operation of said single rotary valve.

5. In combination with a pair of engines, at

least one, having speed regulating means associated therewith, a pair offluid pumps rotatable with said engines, one at a speed corresponding toone engine, the other at a speed corresponding to the other engine,means responsive to a difference in the pressures developed by saidpumps to change the setting of said speed regulating means, saidlast-named means including fluid conduits connecting the inlet of eachpump with the outlet of the other, said fluid conduits having sectionsdisposed in coaxial relationship, means including a single valve forcutting oif fluid flow in said coaxial conduit sections simuling theperiods when fluid flow through said fluid said single valve, saidmanually operable means including fluid receiving means normally incomciated therewith, a pair of fluid pumps rotatable with said engines,'oneat a speed corresponding to one engine, the other at a speedcorresponding to the other engine, means responsive to a diiference inthe pressures developed by said pumps to change the setting of saidspeed regulating means. said last-named means including fluid conduitsconnecting the inlet of each pump with the outlet oi the other, saidfluid conduits 2,254,970 conduits. is interrupted byvirtue of operationof having sections disposed in coaxial relationship. means including asingle valve for cutting oi! fluid flow in said coaxial conduit sectionssimultaneously, manually operable means for changing the setting of saidspeed regulating means during the periods when fluid flow through saidfluid conduits is interrupted by virtue of operation of said singlevalve, said manually operable means including fluid receiving meansnormally in communication with one of said conduits. additional fluidreceiving means normally in communication with the other of saidconduits, both said fluid receiving means being operatively associatedwith said speed regulating means and both being cut oil! from saidfirst-named fluid conduits by movement of said single valve to the flowinterrupting position, and manually operable pumping means fortransferring fluid from one oi said fluid receiving means to the otherindependently of the position of said single valve.

CHARLES I. MACNEIL.

